The White House issued a statement saying The First Lady would not be joining her husband at the international meeting of world leaders in Quebec, Canada, on Friday and Saturday.
It comes after Ms Trump’s five-day stay in hospital in mid-May, when she was treated for a “benign” kidney condition.
She has not been seen in public since 10 May when she and the president welcomed home three Americans who had been held prisoner in North Korea.
It is usual for the spouses of world leaders to attend G7 summits, where they gather at events of their own.
Ms Trump made her international summit debut last year at the G7 meeting in Italy and followed up at the forum of G20 industrialised and developing nations in Germany.
She also missed out on a weekend retreat to Camp David, where Donald Trump, his daughters, eldest son and son-in-law all visited.
Spokeswoman for Ms Trump, Stephanie Grisham, said: “She will not attend the G7 and there are no plans for her to travel to Singapore at this time.”
The meeting in Singapore between Mr Trump and Kim Jong-Un is scheduled for 12 June, but for some time it was unclear whether it would actually go ahead.
The White House initially scrapped the plans after claiming Pyongyang had shown “hostility”, but after some negotiations, it was announced that the talks were back on.
Ms Grisham earlier said the first lady had been meeting with staff and working on projects.
She is expected to join her husband in hosting a reception for Gold Star families – relatives of service members killed in the line of duty – on Monday evening, which is closed to the press.
Responding to media speculation about her absence from the public eye, Melania Trump posted on Twitter last Wednesday: “I see the media is working overtime speculating where I am & what I’m doing.
“Rest assured, I’m here at the @WhiteHouse w my family, feeling great, & working hard on behalf of children & the American people!”
Agencies contributed to this report.